Adding fractions with equal denominators

To add or subtract two like fractions,
simply add or subtract the numerators and put the result over the common denominator,
like this:

Example:

Adding fractions with unequal denominators

To add or subtract fractions don’t have equal denominators, they must first be converted
to equivalent fractions that do have a common denominator. Here are the steps:

Find the least common multiple of the
denominators. When applied to fractions this number is called the least common
denominator (LCD) of the fractions.

Convert each fraction to an equivalent fraction that has the
LCD as its denominator. To do this, multiply the numerator and
denominator of each fraction by the appropriate factor that makes this happen.